The present invention relates generally to seat restraint systems for vehicles and, more particularly, to a seat restraint tensioner for a seat restraint system in a vehicle.
It is known to provide a seat restraint system such as a seat belt in a vehicle to restrain an occupant in a seat of the vehicle. In some vehicles, the seat restraint system may be a lap belt, a shoulder belt, or both. Typically, the lap belt and shoulder belt are connected together at one end. The seat restraint system includes a latch plate at the connected end. The seat restraint system also includes a buckle connected at one end by webbing or the like to vehicle structure. The buckle receives the latch plate to be buckled together. When the buckle and latch plate are buckled together, the seat restraint system restrains movement of the occupant to help protect the occupant during a collision.
It is also known to provide a seat belt tensioner in the seat restraint system for tensioning an occupant belt restraint in the event of sudden vehicle deceleration. An example of such a seat belt tensioner is disclosed in U.S. Pat. No. 5,492,368 to Pywell. In this patent, the seat belt tensioner has a housing with a piston slidably mounted therein and a seat belt reel attached to a shaft of the piston. The seat belt tensioner is operated by pushing a piston with pyrotechnically generated gas and mechanically translating that force into seat belt reeling to wind the belt and seat belt tensioning. However, the force applied by the seat belt is highly dependent on the rate of gas generation, which is difficult to control due to variations in operating pressure, surface area and operating temperatures.
It is desirable to provide a seat restraint tensioner for a seat restraint belt or webbing in a seat restraint system of a vehicle. It is also desirable to provide a seat restraint tensioner with load rate control for a seat restraint system of a vehicle. It is further desirable to provide a seat restraint tensioner having a rate of stroke independent of a rate of gas generation for a seat restraint system in a vehicle. It is still further desirable to provide a seat restraint tensioner for a seat restraint system in a vehicle that is less costly and has a smaller package.
It is, therefore, one object of the present invention to provide a seat restraint tensioner for a seat restraint system in a vehicle.
It is another object of the present invention to provide a seat restraint tensioner for a seat restraint system in a vehicle that applies a force at a controlled rate.
To achieve the foregoing objects, the present invention is a seat restraint tensioner for a seat restraint system in a vehicle including a housing for operative connection to vehicle structure and a movable piston disposed in the housing. The seat restraint tensioner also includes a gas generator operatively connected to the housing for expelling a gas to move the piston. The piston includes a passageway extending therethrough to control a rate of stroke of the piston when the gas is generated to apply a force for pulling-down belt webbing of the seat restraint system.
One advantage of the present invention is that a seat restraint tensioner is provided for a seat restraint system in a vehicle. Another advantage of the present invention is that the seat restraint tensioner has load rate control to pull-down the belt webbing to restraint an occupant in the vehicle. Yet another advantage of the present invention is that the seat restraint tensioner is of a linear type. Still another advantage of the present invention is that the seat restraint tensioner has a rate of stroke independent of a rate of gas generation. A further advantage of the present invention is that the seat restraint tensioner has a relatively low cost, simpler assembly and smaller packaging than current rotary pretensioners.